Quasilinear Parameter-Varying Autopilot Design Using Polynomial Eigenstructure Assignment with Actuator Constraints

Abstract

In this paper, eigenstructure assignment is used in a polynomial matrix framework. In particular, such eigenstructure assignment does not impose any particular eigenvalues and the assignment is done in one-single pass over the flight envelope of a nonlinear missile. The eigenspace of the system is manipulated in polynomial matrix form and the closed-loop transfer function is expressed as a coprime factorization. The designer is left to choose the controller structure producing a flexible design approach. The approach enables the design to consider both static and dynamic controllers alike. In this paper, the approach is applied to a quasilinear parameter-varying missile and it is simple, attractive and comparable to other approaches while leading to a closed-loop system independent of the operating point. The approach is thus similar to dynamic inversion with a self-scheduled controller, but without the need to consider zero dynamics. A tail-controlled missile in the cruciform fin configuration is modeled as a second-order quasilinear parameter-varying system. A lateral velocity controller is designed for the nonlinear model of a tactical missile. The actuator dynamics are included and successively, the actuator dimensioning and the actuator dynamics effects are traded off against performance using the matching conditions developed herein.